1911] on Grouse Disease. 13 



i.e. one free from parasites. A grouse cannot express to us its feel- 

 ings ; the state of its tongue, the rate of its pulse, even its tempera- 

 ture tell us nothing, because we have no norm and no means of 

 estimating the extent to which a diseased bird has departed from 

 the standards of a healthy grouse. The nature of the numerous 

 kinds of blood corpuscles, which alter in proportion so markedly in 

 animals when they become parasitized, was but a few months ago quite 

 unknown, the " blood count " uninvestigated ; in fact, the Inquiry 

 started, as regards the cause and symptoms of the diseases which 

 affect grouse, practically at " scratch." It was, of course, known 

 that the suffering birds lose their activity and are more easily caught 

 than healthy grouse ; their flight is slow and limited in length ; they 

 are said to seek water ; the " call " becomes feeble and hoarse : the 

 feathers of the back and throat lose their lustre and become ruffled ; 

 the eye is dimmed. But these external symptoms may be associated 

 with several diseases and diagnostic of none. Nearly all of them 

 occur in the two diseases Coccidiosis and Strongylosis, which, accor- 

 ding to the Inquiry, are responsible for a very large percentage of 

 deaths among grouse. 



Each of these diseases is caused by an animal parasite, and the 

 investigation of the parasites attracted the attention of the scientific 

 advisers of the Inquiry from an early date. I am afraid that in 

 describing these organisms I shall have to use some rather long 

 words ; in extenuation I can only say, slightly altering Captain 

 Kedgick's retort to Martin Chuzzlewit, " Well ! I didn't fix the zoo- 

 logical language, and I can't unfix it, else I'd make it pleasant." 



Five years ago we knew two internal parasites of the grouse 

 (endoparasites) and two or three parasites which live outside the 

 skin (ectoparasites). At the present time we know that grouse, like 

 other animals, have a considerable fauna living both in and on them. 

 They are in fact not only birds, but in a small way aviating Zoological 

 Gardens. The scientific members of the Inquiry have recorded eight 

 different species of insect or mite living either amongst the feathers 

 or on the skin of the bird or in other ways associated closely with 

 the grouse, and no fewer than fifteen animal parasites living in the 

 blood, the alimentary canal, the lungs, or other organs. Some of 

 these are negligible. They either exist in too small numbers or infest 

 but a very small percentage of the birds ; others, however, are found 

 in about 95 per cent, of the cases investigated, and two at least are 

 associated with grave disorders which often terminate in death. 



The interest of the insects and mites which live on the skin of 

 the bird is that these very likely form the second host of the tape- 

 worms, which undoubtedly do a certain amount of harm to the lining 

 of the alimentary canal. There are, for instance, a couple of species 

 of bird-lice, lively little creatures, which take cover amongst the 

 small feathers — which, by the way, form their arid diet — like startled 

 deer in the undergrowth of a forest. Few grouse are free from these 



